Wireless communication networks provide wireless data services to wireless user devices. Exemplary wireless data services include voice-calling, internet-access, and machine communications. Exemplary wireless user devices comprise phones, computers, drones, and robots. The wireless communication networks have wireless access nodes that exchange wireless signals with the wireless user devices. The wireless signals transport user data and network signaling. The wireless access nodes exchange the user data and network signaling with other network elements to help deliver the wireless data services. Exemplary wireless communication networks include Fifth Generation New Radio (5GNR) networks and Long Term Evolution (LTE) networks.
The wireless communication networks use a technology called Multi-User Multiple Input Multiple Output (MU-MIMO). With MU-MIMO, a wireless access node uses the same time and frequency resources for groups of the wireless user devices. Thus, a group of the wireless user devices shares the same resource blocks using MU-MIMO. Sharing time and frequency resources using MU-MIMO can dramatically improve the spectral efficiency of the wireless communication networks.
To share time and frequency resources using MU-MMO, the wireless access nodes and the wireless user devices use beamforming and signal processing to separate the individual user signals in the shared resource blocks. For successful MU-MIMO reception, the wireless user devices should have a small MU-MIMO correlation factor. The MU-MIMO correlation factor predicts the likely beam interference for a group of wireless user devices sharing resource blocks. A group of wireless user devices that are close to one another have a high MU-MIMO correlation factor because their beams are so close. A group of wireless user devices that are distant from one another have a low MU-MIMO correlation factor because their beams are separated—especially when there is a large angle at the wireless access node between the wireless user devices.
The wireless access points execute Physical Layer (PHY) software to process Sounding Reference Signals (SRS) from the wireless user devices and determine received signal strength, Angle-of-Arrival (AoA), and other radio metrics. The wireless access nodes execute Media Access Control (MAC) software to process the signal strength, AoA, and other radio metrics to determine the MU-MIMO correlation factors between the wireless user devices. If the MU-MIMO correlation factor between a group of wireless user devices is low enough, then the MAC schedules the group of wireless user devices to receive MU-MIMO transmissions over shared resource blocks.
Unfortunately, the calculation of the MU-MIMO correlation factors for the wireless user devices is a heavy burden on the processing resources of the wireless access nodes.